<PAGE>
EXHIBIT 5.1
OPINION OF VENTURE LAW GROUP
October 25, 2000
Foundry Networks, Inc.
2100 Gold Street
P.O. Box 649100
San Jose, CA 95164
Registration Statement on Form S-8
Ladies and Gentlemen:
We have examined the Registration Statement on Form S-8 (the "Registration
------------
Statement") filed by you with the Securities and Exchange Commission (the
---------
"Commission") on October 25, 2000 in connection with the registration under the
-----------
Securities Act of 1933, as amended, of a total of 1,996,188 shares of your
Common Stock (the "Shares") reserved for issuance under the 2000 Non-Executive
------
Stock Option Plan. As your counsel in connection with this transaction, we have
examined the proceedings taken and are familiar with the proceedings proposed to
be taken by you in connection with the sale and issuance of the Shares.
It is our opinion that upon conclusion of the proceedings being taken or
contemplated by us, as your counsel, to be taken prior to the issuance of the
Shares, and upon completion of the proceedings being taken in order to permit
such transactions to be carried out in accordance with the securities laws of
the various states where required, the Shares when issued and sold in the manner
described in the Registration Statement will be legally and validly issued,
fully paid and non-assessable.
We consent to the use of this opinion as an exhibit to the Registration
Statement and further consent to the use of our name wherever appearing in the
Registration Statement, including the Prospectus constituting a part thereof,
and in any amendment thereto.
Sincerely,
VENTURE LAW GROUP
A Professional Corporation
/s/ VENTURE LAW GROUP
